The relatively low voltages employed to power many electronic components are often less than the output voltages of their respective power supplies. For example, some electronic components, such as processors can operate on 1.5 Volts or less, even though their power supplies may provide 3.0 volts or more. Also, many mobile devices conserve energy by including a considerable percentage of electronic components that are powered by voltages that are often substantially less than the terminal voltage of the battery.
A voltage regulating circuit for a battery often bucks (reduces) the battery's terminal voltage with an arrangement of components that provide a fractional gain (less than unity). Also, as a battery discharges and the terminal voltage declines over time, voltage regulation is often provided by switching these components into different phases to provide different fractional gains, e.g., ½, ⅓, ⅖, and the like. For example, a fully charged Lithium Ion battery typically provides a terminal voltage of 4.2 volts or less. Thus, a voltage regulating circuit for a Lithium Ion battery that powers a mobile device would both buck the battery's terminal voltage with a fractional gain and switch to different fractional gains (⅓ to ⅖ to ½, and the like) as the terminal voltage declines over time.
In the past, buck voltage regulating circuits have often used inductive components. However, an inductor produces a relatively large electromagnetic field that can interfere with the operation of radio frequency components included in many mobile devices. Also, the relatively large size of an inductive component can significantly contribute to the cost of manufacturing a voltage regulating circuit.